The automatic transmission shift lock control is a safety device that prevents an inadvertent shift out of PARK when the engine is running. The driver must press the brake pedal before moving the shift lever out of the PARK position. The system consists of the following components.

With the ignition in the ON position, positive battery voltage is supplied to the park relay. When the rear integration module (RIM) energizes the park relay, the park relay switch contacts close suppling battery voltage to the automatic transmission shift lock control switch. The circuit continues through the normally closed switch to the automatic transmission shift lock control solenoid. The permanently grounded solenoid is energized. This locks the shift linkage in the PARK position. When the driver presses the brake pedal, the contacts in the automatic transmission shift lock control switch open. This causes the automatic transmission shift lock control solenoid to release. This allows the shift lever to move from the PARK position. A mechanical locking mechanism prevents the shift lever from moving out of the PARK position when the key is in the OFF position. With the key in the ACC position the mechanical lock is disabled allowing the shift lever to be moved out of the PARK position. This will override the shift lock control system in the event the vehicle must be moved with the engine off.